1. Technical Field
The invention relates to clutch systems and in particular to an automotive clutch system. More particularly, the invention relates to such an automotive clutch system in which the clutch is automatically engaged and is maintained in control of the driver for launch of a drag racing motor vehicle, without blocking manual control of the clutch during power staging of the vehicle at the starting line prior to the start of a race.
2. Background Information
Drag racing of motor vehicles is a sport which has been popular for many years and continues to be popular today. Traditionally, most motor vehicles used in drag racing have manual transmissions rather than automatic transmissions. Therefore, a clutch assembly is required for causing movement of the vehicles having manual transmissions.
Prior to the start of a drag race, a driver typically sees a series of sequentially illuminated lights, usually a red light, a yellow light, and then a green light which signals the start of the race. Each light is illuminated at 0.400 second intervals. Thus, it is critical that the driver reacts to the green light in a timely manner in order to have a good start and be competitive in the race. In a conventional clutch engagement system, launching the vehicle at the start signal involves various foot and leg movements in order to release the clutch and brake pedals for engaging the clutch and unlocking the brakes, respectively.
In addition, when the car is positioned at the starting line before the start of a race, the driver must apply as much power as possible to its driveline without causing the car to move to ensure optimum performance of the car during the race. This technique is called "power staging", and is achieved by locking the brakes of the car and slightly or partially engaging the clutch. This technique removes the slack from the driveline and suspension of the car and poises the car for maximum power application and acceleration. This technique is similar to preventing a car from rolling backward down a hill by using the clutch, and also is similar to engaging the brakes on an automatic transmission car and applying the throttle, thereby preloading the driveline and suspension. Thus, it is apparent that a driver must have precise manual control of the clutch in order to utilize this power staging technique.
The closest known prior art to the present invention is an automatic push button or switch clutch engagement system marketed by McLeod Industries of Anaheim, Calif. This system includes a normally open solenoid valve incorporated into the hydraulic control line between the master and slave cylinders. In operation, the driver of the car depresses a clutch pedal to displace hydraulic fluid from the master to the slave cylinder for releasing the clutch, switches "on"" the solenoid valve which closes and blocks the return of hydraulic fluid to the master cylinder, and then releases the clutch pedal. The valve thus maintains hydraulic pressure in the slave cylinder so that the clutch remains released. When the driver decides to engage the clutch at the start of a race, he merely switches the solenoid valve "off" by a push button switch which opens the valve to release the pressure in the slave cylinder by allowing the hydraulic fluid to return to the master cylinder in a normal fashion. However, it is important to note that when the solenoid valve of the McLeod clutch engagement system is closed, the single hydraulic control line connecting the master and slave cylinders is blocked so that the driver loses manual control of the clutch. Thus, although the McLeod system provides for effective automatic clutch engagement, it interferes with manual control of the clutch which prevents the driver from utilizing the important power staging technique.
Thus, the need exists for an automotive clutch system which automatically engages the clutch of a motor vehicle without blocking manual control of the clutch and that the driver has complete control of the clutch at all times.